The present invention relates to apparatus and methods for web converting machinery, and more particularly to apparatuses and methods for applying adhesive in web converting machinery.
An important objective of most paper converting machinery is to quickly and efficiently produce packaged web product at low cost. For example, machines that operate to attach a sheet of material to a core for winding the material upon the core must perform this operation quickly and consistently for acceptance in the marketplace. As another example, machines that operate to complete a roll of wound product by attaching the tail of the product to the roll must also perform this operation quickly and consistently for acceptance in the marketplace. However, the demand for higher productivity from machines that perform such web rewinding operations has generated significant challenges in machine design.
With reference again to tail sealing operations, there exists a number of well-known ways in which the tail end can be secured or xe2x80x9csealedxe2x80x9d (e.g., by gluing, moistening, etc.) to a log. Each such manner of tail sealing requires some manipulation of the tail end for correct alignment in glue application, proper rewinding, etc. Preferably, the tail of a product log is laid flat and unwrinkled against the log, with the tail being secured to the log at a position a short distance from the end of the tail. This tail sealing arrangement leaves a small length of the end of the tail unsecured to enable the end user to grasp, unseal, and unwind the rolled product. Improper tail end manipulation during the tail sealing process can lead to a number of undesirable results, including inconsistent tail end length and wrinkles in the sealed tail.
Other design challenges involve the application of adhesive to a core, log, or log tail in order to attach a sheet of material to a core or to attach a tail to a log. Although many different devices exist for applying adhesive to sheet product, logs, and cores, conventional adhesive applicators are often inefficient, messy, and require frequent cleaning and maintenance of the adhesive applicator and other equipment exposed to adhesive from the adhesive applicator. Adhesive rollers, brushes, and other applicators are commonly used, but are often slow, take up precious space in sheet rewinding and manipulating machines, and offer little control over the amount of adhesive applied. Although adhesive sprayers offer a number of advantages over rollers, brushes, and other adhesive applicators (including speed and relatively small size), they have not been widely accepted for applying adhesive due to mess from overspray and lack of spray control. As a result of these problems, the design of adhesive applicators in conventional sheet product manipulating apparatuses remains relatively simple and crude at the expense of speed and efficiency.
The foregoing and following discussion concerning the sheet rewinding industry is particularly relevant to paper rewinding. Accordingly, the problems and solutions described below are presented by way of illustration in the context of paper rewinding operations, such as rewinding operations on tissue paper, toilet paper, paper toweling, and the like. However, the present invention is not limited to paper rewinding or even to the paper industry. The present invention finds applicability in any operation in which rolled material is manipulated and/or wound. As such, reference in the present application and appended claims to xe2x80x9clogsxe2x80x9d of material include rolled product made of any material, such as paper, plastic, rubber, metal, composites, fabric, and the like. Also, the rolled product referred to herein and in the appended claims as product in xe2x80x9csheetxe2x80x9d or xe2x80x9cwebxe2x80x9d form can be of any shape and size, including material in sheet, strip, laminate, multi-ply or other form.
A number of conventional adhesive applicator methods and systems exist in the art. However, in order to limit the spread of adhesive in conventional sheet rewinding and manipulating devices, a number of adhesive applicators and applicator designs are not employed. As a result, many current adhesive applicator methods and systems are somewhat crude, providing little control over the amount and placement of adhesive on a tail, log, or core, generating inconsistent adhesive application results, and producing unreliable bonds.
Similarly, a number of conventional tail sealer methods and systems exist in the art. Several of these methods and systems are designed to avoid the aforementioned undesirable results of improper tail manipulation while maintaining a high rate of product output (i.e., sealed logs per minute). However, conventional tail sealers are usually quite complex, employing expensive systems and subsystems to separate and orient a measured length of the tail of each roll in a precise manner, apply adhesive to the tail or log in a precise location, and seal the tail on the log without wrinkling. Four examples of such conventional tail sealers are disclosed in U.S. Pat. No. 5,242,525 issued to Biagiotti, U.S. Pat. No. 4,475,974 issued to Perini, U.S. Pat. No. 3,393,105 issued to C. W. Teller, Jr., and U.S. Pat. No. 5,716,489 issued to Biagiotti. The teachings of the above-listed patents are incorporated herein by reference insofar as they relate to mechanisms and assemblies for manipulating tails of product rolls or logs. Due to their complexity, such conventional systems are invariably expensive and difficult to maintain. Also, an important limitation common to virtually all conventional systems is the maximum speed at which the systems can operate. In modern systems where a fraction of a second in each rewinding operation can significantly impact output and productivity, conventional tail sealing systems typically operate adequately at low speeds but display considerable inefficiencies when run to their highest speeds. The above-mentioned system complexity and bottlenecks caused thereby are often the cause of these inefficiencies. Additionally, such systems are generally less than precise and reliable in their sealing operations, particularly when run at higher speeds.
In light of the problems and limitations of the prior art described above, a need exists for an apparatus and method which can cleanly and reliably apply adhesive to a core, log tail, and/or log in a clean and precise manner, can reliably seal rolled products at a high rate, can produce a consistent and controllable length of tails sealed to the logs, can generate sealed tails which have few to no wrinkles, and can do so by employing a simplified system design which lowers system and maintenance cost. Each embodiment of the present invention achieves one of more of these results.
Some embodiments of the present invention provide an apparatus and method by which adhesive can be applied to a tail of a log of wound product and/or to the log product itself in order to attach the tail to the log. In other embodiments, this apparatus and method is employed to apply adhesive to a core in order to attach sheet product to the core for subsequent winding. The present invention also provides an apparatus and method by which tails of rolled products can be controlled during tail sealing operations of the rolled products.
To quickly accomplish tail sealing operations while maintaining sufficient control of a tail during tail sealing, some preferred embodiments of the present invention include a rotary indexer assembly for controllably feeding rolled products into the tail sealer system, an upper conveyor assembly which rolls the rolled products through the tail sealer system, a lower conveyor assembly which rolls each rolled product within the tail sealer system to unroll the tail to a glue applying position and indexes the proper tail length of each rolled product, an adhesive assembly for applying adhesive to each tail and/or to each rolled product, and an ironing roller assembly which ensures contact between the tail and the rolled product for permitting the adhesive to bond the tail to the rolled product.
In accordance with a preferred method of the present invention, a product roll (or xe2x80x9clogxe2x80x9d) is indexed into the tail sealer system by the indexer assembly. After being indexed, the log is held and preferably rotated in place between the lower conveyor assembly and the upper conveyor assembly. A roll in the lower conveyor assembly is preferably provided to rotate the log in this manner as one or more air jets blow the tail against the roll. In doing so, the length of the tail is preferably measured by a sensor while the roll is precisely indexed.
When the desired tail length has been detected or measured, one or more sprayers spray adhesive upon the unrolled tail and/or upon the log itself. The lower conveyor assembly and the upper conveyor assembly then preferably reverse directions to wind the tail back upon the log. Preferably, the surface speeds of the lower and upper conveyor assemblies are matched during this rewinding operation to keep the roll in place between the lower and upper conveyor assemblies until the tail is fully rewound upon the log. Alternatively, the speeds can be selected to move the log to a roll surface while the tail is being rewound. By gradually being rewound on the log as the log is rotated, the tail of the log is quickly rewound and sealed without wrinkles.
The sealed log is then rolled to the ironing roller assembly for sealing the tail to the log and is finally ejected from the tail sealer system. Preferably, the orientation of the sealed log (the position of the sealed tail upon the log) is known and/or controllable to eject each sealed log from the tail sealer system in a uniform orientation. The orientation of the sealed log is preferably controlled by adjusting the speed and/or the number of rotations of the roller assembly, the conveyor assembly or both assemblies.
In some preferred embodiments of the present invention, an adhesive application assembly having at least one adhesive sprayer and an apertured member is employed to deposit adhesive upon the sheet product. The apertured member is positioned or positionable adjacent to the adhesive application position and has an aperture substantially aligned with the spray trajectory of adhesive from the adhesive sprayers. The apertured member therefore operates as a stencil to permit only a desired pattern of adhesive to pass through the aperture and onto the sheet product in the adhesive application position. This creates an accurate pattern (preferably a line) of adhesive upon the sheet product, does so with less adhesive waste, and generates no appreciable overspray exiting into upstream or downstream equipment.
Some preferred embodiments of the present invention employ an adhesive application assembly that is self-cleaning. Specifically, the apertured member is preferably movable with respect to a cleaning element to bring the apertured member into and out of contact with the cleaning element. Most preferably, the cleaning element is a rotating brush rubbing the apertured member to clean adhesive therefrom. The rotating brush is preferably positioned or positionable within cleaning fluid to assist in the cleaning process. The cleaning element can be movable toward and away from a substantially stationary apertured member, can be substantially stationary and be contacted by a movable apertured member, or can move with the apertured member to contact and clean the apertured member. Other embodiments of the present invention employ cleaning sprayers to spray cleaning fluid upon the movable or substantially stationary apertured member or upon the cleaning element. Among other advantages of the self-cleaning adhesive application assembly, this assembly lowers maintenance costs associated with the equipment in which it is installed and results in better adhesive applicating results over longer periods of time.
As alternatives to using adhesive sprayers in the adhesive application assembly, other adhesive application devices can apply adhesive in conventional manners. For example, an adhesive dip wire, adhesive fountain tip, or one or multiple adhesive applicator roll assemblies can contact the core in the core path to deposit adhesive thereon. In such cases as well as in the preferred embodiment described above, proper product alignment ensures good adhesive application. Such alignment can be provided by sensors and various other measuring devices.
In still other embodiments of the present invention, the adhesive application assembly described above is employed to apply adhesive to cores prior to winding sheet material thereon. The advantages of employing such an adhesive application assembly in preparing cores for winding are similar to those described above for tail sealing.
To help prevent adhesive from exiting the adhesive application position adjacent to the adhesive application assembly and to prevent drafts, dust and other foreign matter from affecting the adhesive application process, some embodiments of the present invention include a dust guard shielding the product in the adhesive application position. Preferably, the dust guard is movable from its shielding position to a retracted position. More preferably, the dust guard is movable to its retracted position in response to movement of the core or sheet product away from the adhesive application position following adhesive application.
More information and a better understanding of the present invention may be achieved by reference to the following drawings and detailed description.